JP7166311B2 - Systems and methods for adaptive buffering for digital video streaming - Google Patents

Description

(Field of Invention)
The present invention relates generally to adaptive streaming, and more particularly to systems for adaptively buffering streaming digital video.

(background)
The term "streaming media" describes the playback of media on a playback device, where the media is stored on a server and continuously transmitted to the playback device over the network during playback. . Typically, the playback device completes playback of all buffered media prior to receipt of the next portion of media, so that the playback device has enough buffers at any given time during playback. amount of media in the buffer to prevent playback interruptions. Adaptive bitrate streaming, or adaptive streaming, involves detecting the present streaming conditions (eg, the user's network bandwidth and CPU capacity) in real time and adjusting the quality of the streamed media accordingly. Typically, the source media is encoded at multiple bitrates, and the playback device or client switches between streaming different encodings depending on available resources.

Adaptive streaming solutions are typically Hypertext Transfer Protocol (HTTP), published by the Internet Engineering Task Force and the World Wide Web Consortium as RFC 2616, or Real-Time Streaming, published by the Internet Engineering Task Force as RFC 2326. Stream media between the server and the playback device using any of the protocols (RTSP). HTTP is a stateless protocol that allows playback devices to request byte ranges within a file. HTTP is described as stateless because, in order to respond to requests received from playback devices, servers are not required to record information about the state of the playback device requesting information or the byte range requested by the playback device. be done. RTSP is a network control protocol used to control streaming media servers. The playback device issues control commands, such as "play" and "pause", to the media streaming server to control playback of the media file. When RTSP is utilized, the media server records the state of each client device and determines media to stream based on instructions received from the client device and the state of the client.

In adaptive streaming systems, source media is typically stored on media servers as top-level index files pointing to several alternative streams containing the actual video and audio data. Each stream is typically stored within one or more container files. Different adaptive streaming solutions typically utilize different indexes and media containers. Synchronous Multimedia Integration Language (SMIL) developed by the World Wide Web Consortium, IIS Smooth Streaming developed by Microsoft Corporation (Redmond, Washington), and Flash Dynamic Streaming developed by Adobe Systems Incorporated (San Jose, Calif.) It is used for indexing in some adaptive streaming solutions, including Developed by Apple Computer Incorporated (Cupertino, Calif.), HTTP adaptive bitrate streaming typically uses extended M3U playlist files (.M3U8 playlist files), which are text files containing a list of URIs that identify media container files. ) to implement the index file. The most commonly used media container formats are the MP4 container format specified in MPEG-4 Part 14 (i.e. ISO/IEC 14496-14) and MPEG-2 Part 1 (i.e. ISO/IEC standard 13818-1). MPEG transport stream (TS) container defined in . The MP4 container format is utilized in IIS Smooth Streaming and Flash Dynamic Streaming. TS containers are used in HTTP adaptive bitrate streaming.

The Matroska container is a media container developed by the Matroska non-profit organization (Aussonne, France) as an open standards project. The Matroska container is based on Extensible Binary Metalanguage (EBML), which is a binary derivative of Extensible Markup Language (XML). Decoding of Matroska containers is supported by many consumer electronics (CE) devices. The DivX Plus file format, developed by DivX, LLC (San Diego, California), utilizes the Matroska container format extension (i.e., is based on the Matroska container format standard but contains elements not specified within the Matroska format). ).

To provide a consistent means for delivery of media content over the Internet, the International Organization for Standardization (ISO) and the International Electrotechnical Commission (IEC) are promoting dynamic adaptive streaming via the HTTP (DASH) standard. is doing. The DASH standard defines formats for media content and content descriptions for the delivery of MPEG content using HTTP. According to DASH, each component of media content for presentation is stored in one or more streams. Each stream is divided into segments. A Media Presentation Description (MPD) is a data structure that contains information about segments within each of the streams and other information needed to represent the media content during playback. Playback devices use the MPD to obtain media content components using adaptive bitrate streaming for playback.

(Summary of Invention)
Systems and methods for adaptive buffering for digital video streaming are illustrated, according to some embodiments of the present invention.

One embodiment includes a playback device comprising a memory, a network interface, and a processor for reading instructions stored in the memory, the instructions downloading digital video content into a buffer of the playback device. receive a minimum buffer time from the digital video content, use the playback device to play the digital video content at slow motion speed, reduce the minimum buffer time by the slow motion playback speed factor, and use the playback device to: Continue playing the digital video content at the slow motion speed until the reduced minimum buffer time is reached, at which time the playback device is used to play the digital video content at a speed faster than the slow motion speed. Instruct the processor to play with

In a further embodiment, downloading the digital video content further comprises requesting a manifest; extracting from the manifest the location of the container file containing the encoded media; and requesting a portion of the file.

In another embodiment, comparing encoded media downloaded in a buffer to a reduced minimum buffer time and using the playback device when the encoded media exceeds the reduced minimum buffer time. to play media encoded with

In still further embodiments, the minimum buffer time is the amount of time to download the minimum amount of media and store it in the buffer to avoid interruptions in playback.

In yet another embodiment, the minimum buffer time is stored within the digital video content in a location selected from the group consisting of a manifest, an index file, and a file pointed to by the digital video content.

In still further embodiments, the digital video content further includes a manifest and multiple container files, each containing an alternate digital video stream.

In yet another embodiment, the alternate digital video stream is a digital video stream encoded at a different bitrate.

In yet a further embodiment, the digital video content is a DASH standard file and the minimum buffer time is stored within the media presentation description data structure.

In yet another embodiment, reducing the minimum buffer time further includes reducing the digital video content and filling the buffer by playing the available digital video content at a reduced speed.

In yet additional embodiments, the slow motion playback speed factor varies the amount of digital video content consumed for playback.

In another additional embodiment, the slow motion speed corresponds to the slow motion playback speed factor.

In still further embodiments, downloading digital video content into a buffer of a playback device using a processor that reads instructions stored in memory; and using a processor that reads instructions stored in memory. receiving a minimum buffer time from the digital video content using a playback device and a processor that reads instructions stored in memory to play back the digital video content at slow motion speed; Using a device to read instructions stored in memory to reduce the minimum buffer time by a slow motion playback speed factor, and a playback device and a processor to read instructions stored in memory and playing back the digital video content at a faster than slow motion speed once the minimum buffer time has been reached.

In still yet another embodiment, downloading the digital video content further comprises requesting the manifest and reading instructions stored in memory using a processor that reads instructions stored in memory. extracting, using a processor, the location of the container file containing the encoded media from the manifest; and using the processor to read instructions stored in memory to locate the container file containing the encoded media. and requesting the potion.

Again in yet a further embodiment, using a processor that reads instructions stored in memory to compare the encoded media downloaded in the buffer with the reduced minimum buffer time and the playing back the encoded media using a playback device when the encoded media exceeds the reduced minimum buffer time using the processor reading the encoded instructions.

Again, in yet another embodiment, the minimum buffer time is the amount of time to download the minimum amount of media and store it in the buffer to avoid interruptions in playback.

In a further embodiment, the minimum buffer time is stored within the digital video content in a location selected from the group consisting of a manifest, an index file, and a file pointed to by the digital video content.

In another embodiment, the digital video content further includes a manifest and multiple container files each containing an alternate digital video stream.

In still further embodiments, the alternative digital video stream is a digital video stream encoded at a different bitrate.

In yet another embodiment, the digital video content is a DASH standard file and the minimum buffer time is stored within the media presentation description data structure.

In still further embodiments, reducing the minimum buffer time further comprises playing the available digital video content at a reduced speed to reduce the digital video content and fill the buffer.

In yet another embodiment, the slow motion playback speed factor varies the amount of digital video content consumed for playback.

In yet further embodiments, the slow motion speed corresponds to the slow motion playback speed factor.
This specification also provides the following items, for example.
(Item 1)
a playback device,
memory;
a network interface;
a processor that reads instructions stored in the memory;
with
Said instruction
downloading digital video content into a playback device buffer;
receiving a minimum buffer time from the digital video content;
playing back the digital video content at slow motion speed using the playback device;
reducing the minimum buffer time by a slow motion playback speed factor;
using the playback device to continue playing the digital video content at the slow motion speed until the reduced minimum buffer time is reached;
using the playback device to play back the digital video content at a speed faster than the slow motion speed once the minimum buffer time is reached;
A playback device that instructs the processor to do
(Item 2)
Downloading said digital video content further comprises:
requesting a manifest;
extracting from the manifest the location of a container file containing encoded media;
requesting a portion of the container file containing encoded media;
A playback device according to item 1, comprising:
(Item 3)
comparing the downloaded encoded media in the buffer to the reduced minimum buffer time;
playing back the encoded media using the playback device when the encoded media exceeds the reduced minimum buffer time;
3. The playback device of item 2, further comprising:
(Item 4)
2. The playback device of item 1, wherein the minimum buffer time is the amount of time to download a minimum amount of media and store it in a buffer to avoid interruptions in playback.
(Item 5)
Playback of item 1, wherein the minimum buffer time is stored within the digital video content in a location selected from the group consisting of a manifest, an index file, and a file pointed to by the digital video content. device.
(Item 6)
6. The playback device of item 5, wherein the digital video content further comprises a manifest and a plurality of container files each containing an alternative digital video stream.
(Item 7)
8. A playback device according to item 7, wherein the alternative digital video stream is a digital video stream encoded at a different bitrate.
(Item 8)
2. The playback device of item 1, wherein the digital video content is a DASH standard file and the minimum buffer time is stored within a media presentation description data structure.
(Item 9)
Playing according to item 1, wherein reducing the minimum buffer time further comprises playing the available digital video content at a reduced speed to reduce the digital video content and fill a buffer. device.
(Item 10)
2. The playback device of item 1, wherein the slow motion playback speed factor varies the amount of the digital video content consumed for playback.
(Item 11)
2. The playback device of item 1, wherein the slow motion speed corresponds to the slow motion playback speed factor.
(Item 12)
A method for providing playback of digital video content, comprising:
downloading digital video content into a buffer of a playback device using a processor that reads instructions stored in memory;
receiving a minimum buffer time from the digital video content using the processor reading the instructions stored in memory;
playing back the digital video content at slow motion speed using the playback device and the processor reading the instructions stored in memory;
reducing the minimum buffer time by a slow motion playback speed factor using the processor reading the instructions stored in memory using the playback device;
playing back the digital video content at a speed faster than the slow motion speed when the minimum buffer time is reached using the playback device and the processor reading the instructions stored in memory;
A method for providing playback of digital video content comprising:
(Item 13)
Downloading said digital video content further comprises:
requesting a manifest using the processor that reads the instructions stored in memory;
extracting the location of a container file containing encoded media from the manifest using the processor reading the instructions stored in memory;
requesting a portion of the container file containing encoded media using the processor reading the instructions stored in memory;
13. A method for providing playback of digital video content according to item 12, comprising:
(Item 14)
comparing the downloaded encoded media in the buffer with the reduced minimum buffer time using the processor reading the instructions stored in memory;
Playing the encoded media using the playback device when the encoded media exceeds the reduced minimum buffer time, using the processor to read the instructions stored in memory. things and
14. A method for providing playback of digital video content according to item 13, further comprising:
(Item 15)
13. The method for providing playback of digital video content according to item 12, wherein the minimum buffer time is the amount of time to download and store in the buffer the minimum amount of media to avoid interruptions in playback.
(Item 16)
13. The digital of claim 12, wherein said minimum buffer time is stored within said digital video content within a location selected from the group consisting of a manifest, an index file, and a file pointed to by said digital video content. A method for providing playback of video content.
(Item 17)
17. A method for providing playback of digital video content according to item 16, wherein the digital video content further comprises a manifest and a plurality of container files each containing an alternative digital video stream.
(Item 18)
18. A method for providing playback of digital video content according to item 17, wherein said alternative digital video stream is a digital video stream encoded at a different bitrate.
(Item 19)
13. A method for providing playback of digital video content as recited in item 12, wherein said digital video content is a DASH standard file and said minimum buffer time is stored within a media presentation description data structure.
(Item 20)
13. The digital device of item 12, wherein reducing the minimum buffer time further comprises reducing the digital video content and filling a buffer by playing the available digital video content at a reduced speed. A method for providing playback of video content.
(Item 21)
13. A method for providing playback of digital video content as recited in item 12, wherein said slow motion playback speed factor varies the amount of said digital video content consumed for playback.
(Item 22)
13. A method for providing playback of digital video content as recited in item 12, wherein said slow motion speed corresponds to said slow motion playback speed factor.

FIG. 1 is a diagram illustrating a network diagram of an adaptive bitrate streaming system, according to an embodiment of the invention. FIG. 2 is a diagram illustrating a playback device of an adaptive bitrate streaming system, according to an embodiment of the invention. FIG. 3 is a diagram illustrating a server of an adaptive bitrate streaming system, according to an embodiment of the invention. FIG. 4 is a flow chart illustrating an adaptive buffering process, according to one embodiment of the invention.

(Detailed Disclosure of Invention)
Turning now to the drawings, systems and methods for providing adaptive buffering of digital video content during playback of video content are illustrated in accordance with many embodiments of the present invention. In some embodiments, it is desirable that a minimum amount of media is stored in the buffer prior to the start of playback of the video in order to reduce the likelihood of playback interruptions to an acceptable level. In various embodiments, this minimum amount of time to download media can be referred to as the minimum buffer time (MBT). The MBT can be stored within the Media Presentation Description (MPD) data structure of the DASH standard. In some embodiments, the MBT may be contained within the manifest and/or within the index file of the MPD data structure. In many other embodiments, the MBT can be contained within the file pointed to by the MPD data structure. The use of the DASH standard is exemplary only, and it is readily apparent that the minimum buffer time (or its equivalent) can be stored in various places within the media manifest and/or within other media file types. should be.

Changes in playback speed (ie, slow motion and/or fast forward) generally change the amount of media consumed for playback. Slow motion playback reduces the amount of media consumed in a given amount of time compared to playback at normal speed. In some embodiments of the invention, reducing the playback speed allows the player to begin playback with less buffered media and without significantly increasing the likelihood of interruptions during playback. can be made possible.

As an illustrative example, media according to some embodiments of the invention has an MBT of 8 seconds. This media will typically buffer 8 seconds of media prior to beginning playback. If the same media is played in slow motion at 1/2 speed, the same media can generally start playing based on a reduced MBT of 4 seconds. Alternatively, if the same media is played in slow motion at 1/4 speed, the same media can start playing based on a reduced MBT of 2 seconds. Additionally, when the media is played at ⅛ slow motion speed, the same media can start playing based on a reduced MBT of 1 second. It should be readily apparent to those skilled in the art that these are examples only and that different media can also be played at different speeds.

Encoding source video for use in an adaptive bitrate streaming system that provides audio playback during trick-play mode and in trick-play mode using adaptive bitrate streaming according to some embodiments of the present invention Playback of media content is discussed further below.

Adaptive Streaming System Architecture Turning now to FIG. 1, an adaptive streaming system including a playback device that provides adaptive buffering is illustrated, according to one embodiment of the present invention. Adaptive streaming system 10 includes a source encoder 12 configured to encode source media as several alternate streams. In the illustrated embodiment, the source encoder is the server. In other embodiments, the source encoder is any process including a processor and sufficient resources to perform transcoding of the source media (including but not limited to video, audio, and/or subtitles). can be a device. Typically, source encoding server 12 generates a top-level index to multiple container files containing stream and/or metadata information, at least some of which are alternate streams. Alternate streams are streams that encode the same media content in different ways. In many instances, alternate streams encode media content (such as, but not limited to, video content and/or audio content) at different maximum bitrates. In some embodiments, alternate streams of video content are encoded at different resolutions and/or different frame rates. The top level index file and container files are uploaded to HTTP server 14 . Various playback devices then request portions of the top-level index file, other index files, and/or container files over a network 16, such as the Internet, using HTTP or another suitable stateless protocol. be able to.

In the illustrated embodiment, playback devices include a personal computer 18, a CE player, and a mobile phone 20. FIG. In other embodiments, the playback device connects to the server via consumer electronics devices such as DVD players, Blu-ray players, televisions, set-top boxes, video game consoles, tablets, and HTTP. and may include other devices capable of playing the encoded media. A specific architecture is shown in FIG. 1, but any of a variety of architectures, including systems that implement conventional streaming rather than adaptive bitrate streaming, can be used by a playback device to perform top-level streaming according to embodiments of the present invention. It can be utilized to allow requesting portions of index files and container files.

Playback Devices Several processes for providing methods and configuring systems according to embodiments of the present invention are performed by playback devices. Relevant components within a playback device capable of implementing processes according to embodiments of the present invention are shown in FIG. Those skilled in the art will recognize that the playback device may include other components omitted for brevity without departing from the described embodiments of the invention. Playback device 200 includes a processor 205 , non-volatile memory 210 and volatile memory 215 . Processor 205 is a processor, microprocessor, controller, or processor, microprocessor, and/or controller that implements instructions stored in volatile 215 or nonvolatile memory 210 and manipulates data stored in memory. is a combination of Non-volatile memory 210 stores processor instructions and/or data for processes being utilized to configure playback device 200 to perform processes, including processes according to embodiments of the present invention. can be done. According to some embodiments, these instructions are included within a playback application that implements playback of media content on a playback device. According to various embodiments, playback device software and/or firmware may be stored on any of a variety of non-transitory computer-readable media suitable for a particular application.

Servers Various processes implemented within an adaptive streaming system, according to different embodiments of the present invention, are performed by HTTP servers, source encoding servers, and/or local and network time servers. Relevant components within the server that implement one or more of these processes, according to embodiments of the present invention, are shown in FIG. Those skilled in the art will recognize that the server may include other components omitted for brevity without departing from the described embodiments of the invention. Server 300 includes a processor 305 , non-volatile memory 310 and volatile memory 315 . Processor 305 is a processor, microprocessor, controller, or processor, microprocessor, and/or controller that implements instructions stored in the volatile 315 or nonvolatile memory 310 and manipulates data stored in the memory. is a combination of Non-volatile memory 310 stores processor instructions utilized and/or data for processes utilized to configure server 300 to implement processes, including processes, in accordance with embodiments of the present invention. can be done. According to some embodiments, instructions for performing encoding of media content are part of an encoding application. In various embodiments, server software and/or firmware may be stored on any of a variety of non-transitory computer-readable media suitable for a particular application. Although a specific server is illustrated in FIG. 3, any of a variety of servers configured to implement any number of processes can be utilized in accordance with embodiments of the present invention. An adaptive buffering process according to many embodiments of the invention is described below.

Adaptive Buffering Process A process for adaptive buffering, according to various embodiments of the present invention, is illustrated in FIG. Process 400 includes receiving a minimum buffer time from digital video content (402). Digital video content can be encoded and stored in any of a variety of formats including (but not limited to) the DASH standard, MPEG-4, and/or Matroska containers. The playback device can then begin downloading the digital video content (404).

The minimum buffer time is reduced 406 as a function of the slow motion playback speed factor. In many embodiments, the slow motion playback speed factor function can vary the amount of media consumed for playback. In various embodiments, the slower the playback speed, the greater the reduction in minimum buffer time. As an illustrative example, media according to some embodiments of the invention has an MBT of 8 seconds. This media will typically buffer 8 seconds of media prior to beginning playback. If the same media is played in slow motion at 1/2 speed, the same media can generally start playing based on a reduced MBT of 4 seconds. Alternatively, if the same media is played in slow motion at 1/4 speed, the same media can generally start playing based on a reduced MBT of 2 seconds. Additionally, when the media is played at ⅛ slow motion speed, the same media can generally start playing based on a reduced MBT of 1 second. It should be readily apparent to those skilled in the art that these are examples only and that different media can also be played at different speeds.

Digital video content begins playing in slow motion (408). In many embodiments, digital video content will begin playing when the MBT buffer is full. In some other embodiments, playback begins before the MBT buffer is full. As an illustrative example, playback may begin when the MBT buffer is 75% full when the available bandwidth is significantly higher than the bitrate of the digital video content. This is only an example, and playback of digital video content may vary within a system, including (but not limited to) bandwidth, bitrate, MBT buffer size, playback speed factor, and/or system hardware requirements. It should be readily apparent to one of ordinary skill in the art that the .

The slow motion digital video content continues to play (410) until the reduced minimum buffer time is reached. Although various processes for adaptively buffering digital video content are described above with respect to FIG. 4, any of the various processes that are capable of reducing the minimum buffer time may be used in accordance with various aspects of the present invention. can be utilized as appropriate to specific application requirements according to embodiments of

In some embodiments of the present invention, slow motion playback speed and/or audio playback may increase (or gradually increase) as MBT increases. In many embodiments of the present invention, the playback speed and/or audio playback is as the MBT increases such that the playback speed and/or audio playback will be at full speed when the MBT is reached. can be incremental.

In other embodiments of the invention, the process can detect when the buffer falls below a threshold and gradually reduce the playback speed and/or audio playback until the buffer can recover. This may attempt to delay stopping the playback of video and/or audio streams with gradual deterioration in playback (as opposed to video and/or audio streams that play and then stop). In general, this can occur in situations that delay switching down to lower bitrate and/or lower quality video streams. Alternatively, if the video and/or audio stream is in the lowest quality stream, playback can be slowed down until better bandwidth can be achieved. In general, embodiments of the present invention delay the stopping of the stream as long as possible through slow-motion playback, rather than stopping playback according to various embodiments of the present invention. can be done.

Although the present invention has been described in certain specific aspects, many additional modifications and variations will become apparent to those skilled in the art. Accordingly, the present invention covers various modifications of implementation, such as the use of encoders and decoders, to support features other than those specified in the particular standards to which they comply without departing from the scope and spirit of the invention. It should be understood that other practices than those specifically described may be practiced, including . Accordingly, embodiments of the present invention are to be considered in all respects as illustrative rather than restrictive.

Claims (14)

a playback device,
memory;
a network interface;
a processor that reads instructions stored in the memory;
Said instruction
receiving a manifest file containing information about a plurality of alternate streams, each alternate stream having a different bitrate than the other streams;
Receiving a minimum buffer time for each alternate stream from the manifest file, wherein the minimum buffer time for each alternate stream is determined by the alternate stream to prevent interruption of playback of the digital video content at the normal speed of playback of the alternate stream. is a predetermined playing time of the stream's digital media content;
Determining a reduced minimum buffer time for each alternate stream from the manifest file, wherein the reduced minimum buffer time for each alternate stream is a numerical factor of the minimum buffer time for the alternate stream at the normal speed of playback. divided by, said numerical factor being greater than 1;
downloading the digital video content of a first alternative stream into a buffer of the playback device;
commencing playback of the digital video content when the amount of digital content of the first alternative stream in the buffer first reaches the reduced minimum buffer time, said initiated playback. is a slow motion speed equal to the speed of the normal speed of the first alternative stream reduced by the numerical factor. Downloading said digital video content further comprises:
extracting from the manifest file the location of a container file containing encoded media;
and requesting a portion of the container file containing encoded media. 2. The playback device of claim 1, wherein the digital video content is a DASH standard file and the minimum buffer time is stored within a media presentation description data structure. 2. The method of claim 1, wherein reducing the minimum buffer time further comprises reducing the digital video content and filling a buffer by playing available digital video content at a reduced speed. playback device. The playback device of Claim 1, wherein the numerical factor varies the amount of the digital video content consumed for playback. 2. The playback device of Claim 1, wherein the slow motion speed corresponds to the numerical factor. A method for providing playback of digital video content, comprising:
Receiving a manifest file using a processor that reads instructions stored in memory, the manifest file containing information about a plurality of alternate streams, each alternate stream being different from the other streams. having a bitrate;
Receiving a minimum buffer time for each alternate stream from the manifest file using the processor reading the instructions stored in memory, wherein the minimum buffer time for each alternate stream is determined for playback of the alternate stream. a predetermined playback time of the digital media content of the alternate stream to prevent interruption of playback of the digital video content at normal speed;
Determining a reduced minimum buffer time for each alternate stream from the manifest file using the processor reading the instructions stored in memory, wherein the reduced minimum buffer time for each alternate stream is , the minimum buffer time of the alternative stream at the normal speed of playback divided by a numerical factor, the numerical factor being greater than one;
downloading said digital video content of a first alternative stream into a buffer of a playback device using said processor reading said instructions stored in memory;
Using the processor to read the instructions stored in memory, when the amount of digital content of the first alternative stream in the buffer first reaches the reduced minimum buffer time, the digital initiating playback of video content, wherein the speed of playback initiated is a slow motion speed equal to the normal speed of the first alternative stream reduced by the numerical factor. , a method for providing playback of digital video content. Downloading said digital video content further comprises:
extracting the location of a container file containing encoded media from the manifest file using the processor reading the instructions stored in memory;
requesting a portion of the container file containing encoded media using the processor that reads the instructions stored in memory. How to. 8. The method for providing playback of digital video content as recited in claim 7, wherein said digital video content is a DASH standard file and said minimum buffer time is stored within a media presentation description data structure. 8. The method of claim 7, wherein reducing the minimum buffer time further comprises reducing the digital video content and filling a buffer by playing available digital video content at a reduced speed. A method for providing playback of digital video content. 8. The method for providing playback of digital video content as recited in claim 7, wherein said numerical factor varies the amount of said digital video content consumed for playback. 8. A method for providing playback of digital video content as recited in claim 7, wherein said slow motion speed corresponds to said numerical factor. The instructions stored in the memory further comprise:
continuing playing the digital video content at the slow motion speed until the digital content of the first alternative stream in the buffer reaches the minimum buffer time;
playing the digital video content at the normal speed of playback when the digital content of the first alternate stream in the buffer reaches the minimum buffer time. device. Providing playback of digital video content further
said digital video at said slow motion speed until said digital content of said first alternative stream in said buffer reaches said minimum buffer time using said processor reading said instructions stored in memory; continuing to play the content; and
The processor reading the instructions stored in memory is used to read the digital content of the first alternative stream in the buffer at the normal speed of playback when the digital content of the first alternative stream in the buffer reaches the minimum buffer time. 8. The method of claim 7, comprising playing video content.

Images